I agree with Don. #1 is a nice example of a legitimate flat back PAB. The rest, #2, #3, and #4 all have the telltale flatback which sets off alarm bells and whistles. All of those badges should have a slightly dished back. Check out Stogieman's Hermann Aurich PAB in the Sale Room and note the shape of the back compared to your example. Also check out that thread I referred you to in your earlier post. The guys have some great examples of various makers badges ranging from common to exceedingly rare.